In indirect extrusion, the counter platen of the press is generally provided with a stationary hollow press stem which supports at its free front end a die which is arranged in a disc, the so-called die holder. A sealing plate is provided between the billet container and the moving crosshead of the press and seals the bore of the billet container from the moving crosshead. During extrusion, the billet container, together with the billet located in its bore is pushed over the stationary hollow stem, whereby the press charge is pressed through the die and the hollow stem and out through a larger opening in the counter platen.
Depending on the press programme, the die may be provided with, for example, two bores for two-core wire extrusion. In order to guide the two wire cores in the hollow stem without them touching each other, two guide tubes are provided in the hollow stem. The die holder together with the die fixed therein must be pushed onto the hollow stem in such a manner that the die apertures in the die line up exactly with the guide tubes located in the hollow stem.
The dies must be removed and cleaned at intervals, and then must be lifted again to the centre of the hollow stem, rotated into the aligning position and pushed onto the stem.